Datasheet
181
8246A–AVR–11/09
ATtiny2313A/4313
Notes: 1. See section “Signature Bytes” for more information.
2. See section “Calibration Byte” for more information.
20.3.1 Calibration Byte
The signature area of the ATtiny2313A/4313 contains two bytes of calibration data for the inter-
nal oscillator. The calibration data in the high byte of address 0x00 is for use with the oscillator
set to 8.0 MHz operation. During reset, this byte is automatically written into the OSCCAL regis-
ter to ensure correct frequency of the oscillator.
There is a separate calibration byte for the internal oscillator in 4.0 MHz mode of operation but
this data is not loaded automatically. The hardware always loads the 8.0 MHz calibration data
during reset. To use separate calibration data for the oscillator in 4.0 MHz mode the OSCCAL
register must be updated by firmware. The calibration data for 4.0 MHz operation is located in
the high byte at address 0x01 of the signature area.
20.3.2 Signature Bytes
All Atmel microcontrollers have a three-byte signature code which identifies the device. This
code can be read in both serial and parallel mode, also when the device is locked. The three
bytes reside in a separate address space.
For the ATtiny2313A the signature bytes are:
1. 0x000: 0x1E (indicates manufactured by Atmel).
2. 0x001: 0x91 (indicates 2KB Flash memory).
3. 0x002: 0x0A (indicates ATtiny2313A device when 0x001 is 0x91).
For the ATtiny4313 the signature bytes are:
1. 0x000: 0x1E (indicates manufactured by Atmel).
2. 0x001: 0x92 (indicates 4KB Flash memory).
3. 0x002: 0x0D (indicates ATtiny4313 device when 0x001 is 0x92).
20.4 Page Size
Table 20-7. No. of Words in a Page and No. of Pages in the Flash
Device Flash Size Page Size PCWORD No. of Pages PCPAGE PCMSB
ATtiny2313A
1K word
(2K bytes)
16 words PC[3:0] 64 PC[9:4] 9
ATtiny4313
2K words
(4K bytes)
32 words PC[4:0] 64 PC[10:5] 10
Table 20-8. No. of Words in a Page and No. of Pages in the EEPROM
Device
EEPROM
Size Page Size PCWORD No. of Pages PCPAGE EEAMSB
ATtiny2313A 128 bytes 4 bytes EEA[1:0] 32 EEA[6:2] 6
ATtiny4313 256 bytes 4 bytes EEA[1:0] 64 EEA[7:2] 7